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		<h1>[name]</h1>

		<p class="desc">
			Handles and keeps track of loaded and pending data. A default global instance of this class
			is created and used by loaders if not supplied manually - see [page:DefaultLoadingManager].<br /><br />

			In general that should be sufficient, however there are times when it can be useful to have separate loaders -
			for example if you want to show separate loading bars for objects and textures.

		</p>

		<h2>Code Example</h2>

		<p>
			This example shows how to use LoadingManager to track the progress of
			[page:OBJLoader].
		</p>

		<code>
		const manager = new THREE.LoadingManager();
		manager.onStart = function ( url, itemsLoaded, itemsTotal ) {

			console.log( 'Started loading file: ' + url + '.\nLoaded ' + itemsLoaded + ' of ' + itemsTotal + ' files.' );

		};

		manager.onLoad = function ( ) {

			console.log( 'Loading complete!');

		};


		manager.onProgress = function ( url, itemsLoaded, itemsTotal ) {

			console.log( 'Loading file: ' + url + '.\nLoaded ' + itemsLoaded + ' of ' + itemsTotal + ' files.' );

		};

		manager.onError = function ( url ) {

			console.log( 'There was an error loading ' + url );

		};

		const loader = new THREE.OBJLoader( manager );
		loader.load( 'file.obj', function ( object ) {

			//

		} );
		</code>

		<p>
			In addition to observing progress, a LoadingManager can be used to
			override resource URLs during loading. This may be helpful for assets
			coming from drag-and-drop events, WebSockets, WebRTC, or other APIs. An
			example showing how to load an in-memory model using Blob URLs is below.
		</p>

		<code>
		// Blob or File objects created when dragging files into the webpage.
		const blobs = {'fish.gltf': blob1, 'diffuse.png': blob2, 'normal.png': blob3};

		const manager = new THREE.LoadingManager();

		// Initialize loading manager with URL callback.
		const objectURLs = [];
		manager.setURLModifier( ( url ) => {

			url = URL.createObjectURL( blobs[ url ] );

			objectURLs.push( url );

			return url;

		} );

		// Load as usual, then revoke the blob URLs.
		const loader = new THREE.GLTFLoader( manager );
		loader.load( 'fish.gltf', (gltf) => {

			scene.add( gltf.scene );

			objectURLs.forEach( ( url ) => URL.revokeObjectURL( url ) );

		});
		</code>

		<h2>Examples</h2>

		<p>
			[example:webgl_loader_obj WebGL / loader / obj]<br />
			[example:webgl_materials_physical_reflectivity WebGL / materials / physical / reflectivity]<br />
			[example:webgl_postprocessing_outline WebGL / postprocesing / outline]
		</p>

		<h2>Constructor</h2>

		<h3>[name]( [param:Function onLoad], [param:Function onProgress], [param:Function onError] )</h3>
		<p>
		[page:Function onLoad] — (optional) this function will be called when all loaders are done.<br />
		[page:Function onProgress] — (optional) this function will be called when an item is complete.<br />
		[page:Function onError] — (optional) this function will be called a loader encounters errors. <br />

		Creates a new [name].
		</p>


		<h2>Properties</h2>

		<h3>[property:Function onStart]</h3>
		<p>
			This function will be called when loading starts.
			The arguments are:<br />
			[page:String url] — The url of the item just loaded.<br />
			[page:Integer itemsLoaded] — the number of items already loaded so far.<br />
			[page:Integer itemsTotal] — the total amount of items to be loaded.<br /><br />

			By default this is undefined.
		</p>

		<h3>[property:Function onLoad]</h3>
		<p>
			This function will be called when all loading is completed. By default this is undefined,
			unless passed in the constructor.
		</p>

		<h3>[property:Function onProgress]</h3>
		<p>
		This function will be called when an item is complete.
		The arguments are:<br />
		[page:String url] — The url of the item just loaded.<br />
		[page:Integer itemsLoaded] — the number of items already loaded so far.<br />
		[page:Integer itemsTotal] — the total amount of items to be loaded.<br /><br />

		By default this is undefined, unless passed in the constructor.
		</p>

		<h3>[property:Function onError]</h3>
		<p>
			This function will be called when any item errors, with the argument:<br />
			[page:String url] — The url of the item that errored.<br /><br />

			By default this is undefined, unless passed in the constructor.
		</p>


		<h2>Methods</h2>

		<h3>[method:this addHandler]( [param:Object regex], [param:Loader loader] )</h3>
		<p>
		[page:Object regex] — A regular expression.<br />
		[page:Loader loader] — The loader.
		<p>
		Registers a loader with the given regular expression. Can be used to define what loader should be used in
		order to load specific files. A typical use case is to overwrite the default loader for textures.
		</p>
		<code>
// add handler for TGA textures
manager.addHandler( /\.tga$/i, new TGALoader() );
		</code>

		<h3>[method:Loader getHandler]( [param:String file] )</h3>
		<p>
		[page:String file] — The file path.
		<p>
		Can be used to retrieve the registered loader for the given file path.
		</p>

		<h3>[method:this removeHandler]( [param:Object regex] )</h3>
		<p>
		[page:Object regex] — A regular expression.
		<p>
		Removes the loader for the given regular expression.
		</p>

		<h3>[method:String resolveURL]( [param:String url] )</h3>
		<p>
		[page:String url] — the url to load<br /><br />

		Given a URL, uses the URL modifier callback (if any) and returns a resolved URL. If no
		URL modifier is set, returns the original URL.
		</p>

		<h3>[method:this setURLModifier]( [param:Function callback] )</h3>
		<p>
		[page:Function callback] — URL modifier callback. Called with [page:String url] argument, and
		must return [page:String resolvedURL].<br /><br />

		If provided, the callback will be passed each resource URL before a request is sent. The
		callback may return the original URL, or a new URL to override loading behavior. This
		behavior can be used to load assets from .ZIP files, drag-and-drop APIs, and Data URIs.
		</p>

		<br />

		<p>
			<em>Note: The following methods are designed to be called internally by loaders. You shouldn't call
			them directly.</em>
		</p>

		<h3>[method:undefined itemStart]( [param:String url] )</h3>
		<p>
		[page:String url] — the url to load<br /><br />

		This should be called by any loader using the manager when the loader starts loading an url.
		</p>

		<h3>[method:undefined itemEnd]( [param:String url] )</h3>
		<p>
		[page:String url] — the loaded url<br /><br />

		This should be called by any loader using the manager when the loader ended loading an url.
		</p>

		<h3>[method:undefined itemError]( [param:String url] )</h3>
		<p>
		[page:String url] — the loaded url<br /><br />

		This should be called by any loader using the manager when the loader errors loading an url.
		</p>

		<h2>Source</h2>

		<p>
			[link:https://github.com/mrdoob/three.js/blob/master/src/loaders/LoadingManager.js src/loaders/LoadingManager.js]
		</p>
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